264 Mr, O. Thomas on Gerbils 
the plateau by réchardi *, and south of the Atlas by guyont. 
Then the large-bulla group b is represented south of the 
Atlas by schousboed (a form doubtfully separable from bycus), 
but is not found to the north of the range. 
Working eastwards, we have in Tripoli local representatives 
of a, 6, and c ranging widely over the country, which is not 
broken up by any prominent orographical features. Two of 
these seem to need new subspecific names, 
Next, in Egypt we have first of all the comparatively 
bushy-tailed animal, called quite unaccountably by de Winton t 
“M. crassus sellysit”’ (sic), which was obtained by Mr. N.C. 
Rothschild in the Wadi Natron, and which I identify: with 
Meriones libycus, Lichtenstein, the first African name in the 
genus, but one hitherto altogether ignored. The locality, 
dimensions, and the “ caud& apice floccosa” all agree with 
the Wadi Natron animal, and there seems no reason to doubt 
the identification, 
With libycus I also synonymize Riippell’s melanurus, 
which has been a prime source of confusion, for not only did 
he include both Alexandria and Sinai as its habitat, but he 
sent out specimens under its name which are referable to 
forms of both group 6 and group ¢. For of the two examples 
of it that he sent to the British Museum no. 42. 8. 15. 2 is 
the bushy-tailed 6 species, while 42. 8. 15. 6 belongs to c. 
In consequence, it appears to be necessary now for me, as 
the first reviser who has a knowledge of the mixture of the 
two species, definitely to determine on to which the name 
melanurus shall be placed. 
I therefore propose formally to apply it to the one with a 
prominently black-tufted tail, as Riippell evidently meant, 
making the name itself suitable, even though then becoming 
synonymous with lidycus. 
The other course would result in the species with the least 
black on its tail bearing the inappropriate name melanurus. 
In order to make this definite I propose to select as a 
lectotype of melanurus B.M. no. 42. 8. 15. 2, sent as a co-type 
of it by Riippell in conjunction with 42. 8.15.6, which is 
* In dealing with Loche’s many names, applied to animals with exact 
localities recorded, but without any mention of the bull, I have thought 
it best, in view of the admirable pioneer work he has done on the 
genus, to accept Lataste’s reference of them to their respective groups 
(his “shawi” being ¢ group and his erythrurus 6 group), and then to 
take the first name in each group according to its locality, and so identify 
them, 
+ Noy. Zool. x. p. 284 (1903). The type of selysii was from Oran, and 
the name is an absolute synonym of shaw. On the other hand, ecrassus 
was from Sinai, and is a wholly different species, belonging to group a. 
